理解PHP中的依赖注入

Question

class Author {
    private $firstName;
    private $lastName;

    public function __construct($firstName, $lastName) {
        $this->firstName = $firstName;
        $this->lastName = $lastName;
    }

    public function getFirstName() {
        return $this->firstName;
    }

    public function getLastName() {
        return $this->lastName;
    }
}

class Question {
    private $author;
    private $question;

    public function __construct($question, Author $author) {
        $this->author = $author;
        $this->question = $question;
    }

    public function getAuthor() {
        return $this->author;
    }

    public function getQuestion() {
        return $this->question;
    }
}

Class author is injected into the constructor of Question class am I correct? but how to call the Question class to get the author's name?

$question = new Question('What is PHP', 'Adam');
$question->getFirstname;

like this? I assume Question class inherited Author class so Question's instance can use the function of Author Class?

Answer 1

Simple

echo $question->getAuthor()->getFirstName();

Think of it this way if it helps

$author = $question->getAuthor();
echo $author->getFirstName();

Also note that you can't construct a Question with the string "Adam", you need to pass an instance of Author

$question = new Question('What is PHP', new Author('Adam', 'Lastname'));